A metal insulator semiconductor field effect transistor (MISFET or MIS field effect transistor) has been known as a semiconductor element which is used as a switching element or the like. Examples of the MISFET include a low breakdown voltage MISFET which is used in a peripheral circuit such as a logic circuit and a high breakdown voltage MISFET which is used in a memory cell or for input and output of power, and these MISFETs are consolidated in a single semiconductor chip in some cases.
Japanese Patent Application Laid-Open Publication No. 2004-349680 (Patent Document 1) and Japanese Patent Application Laid-Open Publication No. 2014-075557 (Patent Document 2) describe techniques of forming a relatively wide sidewall that covers sidewalls of agate electrode of a transistor and a relatively narrow sidewall that covers sidewalls of a gate electrode of another transistor.